Process for recovering copper from the wash liquors employed in the cuprammonia-cellulose process.



B. BRONNERT. PROCESS FOR REGOVERING COPPER FROM THE WASH LIQUOESEMPLOYED IN THE GUPRAMMONIA GELLULOSE PROOF-SS. APPLICATION FI LEDJAN.14, 1911.

Patented Dec. 31, 1912.

VY/ T'NES ES' TED sra'rns PAT QB-TC.

EMILE BRONNER-T, 0F NIEDERMORSCHWEILER, GERMANY, ASSIGNOR TO VEREINIGTEGLANZS'IOFF-FABRIKEN A. G., OF ELBERFELD, GERMANY.

PROCESS FOR 'RECOV'ERING COPPER FROM THE WASH LIQUORS EMPLOYED IN THECUPRAMMONIA-CELLULOSE PROCESS.

roaaaoi.

Specification of Letters Patent. J Patented Dec. Sit, 11912.

Application filed'january 14, 1911., Serial No. 602,725.

To all whom it may concern;

Be it known that I, EMILE BRONNERT, a subject of the German Emperor,residing at Niedermorschweiler, Germany, have in vented certain new anduseful Improvements in the Process for Recovering Copper from the'lV-ash Liquors Employed in the Cu 1)ra1nmoniaCellulose Process, ofwhich the following is a specification.

lf ammonia is expelled from an alkaline cuprammonia solution (such as isproduced,

for instance, by the absorption of ammoniabearing gases by wash liquorsresulting from the manufacture of cellulose articles, such as filaments,threads, films and the like, from cuprammonia cellulose solutions byprecipitation with alkaline agents, such as sodium saccharate, andsubsequent washing with water) by means of a current of steam which isled in contact with and in the opposite direction to, the liquidtrickling down in a suitable apparatus, the copper contained in thesolution will be reduced to an oxidof copper, such as the brown cuprousoxid, and partly even to metallic copper. Such reduced copper and011])1'0118 oXid cannot be completely separated from the supernatantliquid by settling; but may be transformed after separation, by heatingin the air, into cupric oxid which may be used again in the cycle ofoperations. I have found that the copper and the oxid of copper caneasily be almost entirely recovered from the relatively large quantitiesof wash liquors if small amounts of certain colloids (either as such orfirst stirred in water) are mixed (under agitation) with the hot liquorsflowing from the distilling apparatus. This causes the copper or theoxid to form balls or globules.

Experiments have shown that starch is the cheapest and most practicalagent for this by the following example: Into the hot,

weakly alkaline liquor flowing from the ammonia distilling column andcontaining the cuprous oxid or even metallic copper in a state ofexceedingly fine suspension, I add a stream of a milk-like liquid madeby -stirring starch incold water, the amount added being such that therewill be about 1 kilogram of starch for each 10 cubic meters of alkalineliquor. The mixture may be accomplished automatically by causing onestream to fiow into the other.

According to the greater or less alkalinity of the liquors the amount ofstarch maybe slightly increased or diminished. H the al kalinity of theliquors is too great, which would cause the starch to lose its colloidalcharacteristics, the liquors may be diluted sodium hydrate (-NaOH) to 1liter of water in a solution in which soda is used as the alkalineprecipitating agent. The starch used may be the commercial article oflowest quality and of any vegetable ext-raction (as for instancewheat-starch, rice-starch, )almstarch, etc). The agglutination is connoted in the manner described above preferably in the hot liquid itself,as the agglomeration of the copper or its oxid will then proceed mostefficiently and rapidly. The proper proportioning of the addition may beascertained by removing a test portion, in which the slime should settleat once,'leaving an absolutely clear supernatant liquid.

It is 0bviouscopper may be recovered by the present process from washliquors whichhave not been used to absorb ammonia freed in theprecipitating operation, but which come directly from a washing vat orthe like.

Starch has been mentioned herein as the specific colloidalcarbo-hy-drate employed,

but other specific carbo-hydrates of the class of cellulose may beemployed instead, as

inulin, lichenin, deXtrin, bassorin (Carrageenin) or wood-celluloseforming acolloidal pap.

An apparatus in which the process may be carried out, is illustrateddiagrammatically in the accompanying drawing, in which A is a tankcontainin,, the Wash liquors, containing ammonia in solution, from whichthe copper is to be recovered, and B is a column through which the washliquors trickle or drip preferably in the. opposite direction to acurrent of hot fluid, as

roaaaoi 5 steam. The wash liquors are preferably pumped from the vat Ato the upper part of the column B by means of a pump a. The wash liquorsare also preferably heated prior to reaching the column B by beingpassed through a dephlegmator or heating coil 6. Steam maybe admitted tothe lower end ofthe column B through a cock The freed ammonia and steammay flow 0H through the pipe 12 into the dephlegmator Z) and out throughthe pipe b From the bottom of the column, the wash liquor, freed fromthe ammonia flows out through the cock 6* into a vat d, where it ismixed with a colloidal solution, which may be admitted from a tank D. Anagitator c is referably provided for more thoroughly efl ecting themixture of the liquids. Acseries of settling tanks E, arra'nged'incascade, into which the mixture may be pumped by a pump 6, may beprovided in which the agglomeration may settle and be collected, thewater flow-- ing oil clear from the spout e at the end of the cascade. j

Wash liquors which have not been used to absorb ammonia from theprecipitatin bath, may be admitted directly to the vat and mixed'withthe agglutinating solution.

I claim as my invention 1. The process of recovering copper from thewash liquors employed in the manutao" ture of artificial cellulosearticles from cuprammonium cellulose solutionswhichliquors have beenused for absorbing ammonia, which process comprises removing the ammoniafrom the liquors by distillation, adding small quantities of a colloidalcarbohydiets of the class of cellulose, and separating the agglomeratedmass from the alkaline liquor.

2. The process of recovering copper from the Wash liquors employed inthe manufacture of artificial cellulose articles from cuprammoniumcellulose solutions which liquors have been used for absorbing ammonia,

which process comprises removing the ammonia from the liquors bydistillation, adding small quantities of a colloidal carbohydrate of theclass of cellulose, and separat ing the agglomeratedmass from thealkaline liquor by decantation.

. 3. The process of recovering copper from the wash liquors employed inthe manufac ture of artificial cellulose articles from cuprammoniumcellulose solutions which liquors have been used for absorbing ammonia,

monlum cellulose soluions, which process comprises addingsmallquantities of a col loidal carbohydrate of the class of cellulose to thewash liquors, and separating the agglomerated mass from the alkalineliquor.

5. The process of recovering copper from wash liquors employed in themanufacture of artificial cellulose articles from cupraur moniumcellulose solutions, which liquors have been used for absorbing ammonia,

which process comprises removing the .am-

ing small quantities of starch to the wash liquors, and separating theagglomerated mass from the alkaline liquor. L

. 6. The process of recovering copper from wash liquors employed in themanufacturev of artificial cellulose articles from cuprammoniumcellulose solutions, which process comprises adding small quantities ofstarch to the wash liquors, and separating the.

agglomeratedqnass from the alkaline liquor.

,monia from the liquors by distillation, add- In witness whereof, I have"hereunto signed-my namein the presence of two subscribing witnesses. g

. i EMILE BRONNERT. Witnesses; JOSEPH WILLARD,

.; WALTER J, sums.

